9x^2-21+4=0

Solution for 9x^2-21+4=0 equation:

Simplifying
9x2 + -21 + 4 = 0

Reorder the terms:
-21 + 4 + 9x2 = 0

Combine like terms: -21 + 4 = -17
-17 + 9x2 = 0

Solving
-17 + 9x2 = 0

Solving for variable 'x'.

Move all terms containing x to the left, all other terms to the right.

Add '17' to each side of the equation.
-17 + 17 + 9x2 = 0 + 17

Combine like terms: -17 + 17 = 0
0 + 9x2 = 0 + 17
9x2 = 0 + 17

Combine like terms: 0 + 17 = 17
9x2 = 17

Divide each side by '9'.
x2 = 1.888888889

Simplifying
x2 = 1.888888889

Take the square root of each side:
x = {-1.374368542, 1.374368542}